jme3-plugins loads MorphPrimitivesTest incorrectly

[stephengold]

I noticed a defect in GltfLoader while developing the MonkeyWrench library.

The test data is MorphPrimitivesTest from Khronos's glTF sample models.

Here's how it looks in CompareLoaders when "MorphPrimitivesTest/glTF/MorphPrimitivesTest.gltf" is loaded using jme3-plugins:

I believe the best approach to solve this issue will be:

1. Add a MorphControl to every model with morph targets, even if there are no animation tracks.
2. Initialize the morph state of each Geometry by invoking setMorphState() with the "weights" values in the glTF.

[riccardobl]

Is this fixed by #2109 ?

[codex128]

No, I've already tried MorphPrimitivesTest with #2109 and it still fails. I suspect this is because the gltf file does not explicitly define animations (unlike the MorphStressTest gltf).